Is a computed tomography (CT) head scan with or without contrast indicated for a patient presenting with syncope?

From the Guidelines

For syncope evaluation, a non-contrast CT head scan is typically recommended, but only in cases with concerning neurological symptoms, signs of head trauma, or risk factors for intracranial pathology, as stated in the 2021 ACR Appropriateness Criteria for syncope 1. This approach is based on the understanding that the primary concern in syncope is ruling out structural abnormalities like intracranial hemorrhage, mass lesions, or hydrocephalus that might explain the loss of consciousness. The use of contrast is generally unnecessary for these purposes and adds potential risks including allergic reactions, contrast-induced nephropathy, and increased cost without providing significant additional diagnostic value for the common causes of syncope. According to the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope, MRI and CT of the head are not recommended in the routine evaluation of patients with syncope in the absence of focal neurological findings or head injury that support further evaluation 2. Key points to consider in the evaluation of syncope include:

• A detailed history and physical examination to identify potential causes and risk factors
• Selective use of neuroimaging based on clinical assessment
• Consideration of cardiac-related symptoms and risk factors that may guide additional testing
• Avoidance of routine head CT or MRI in uncomplicated syncope cases, as supported by multidisciplinary task forces and clinical guidelines 1. In cases where neuroimaging is deemed necessary, a non-contrast CT head scan is preferred due to its ability to quickly and effectively rule out life-threatening conditions without the added risks associated with contrast material. Ultimately, the decision to perform a CT head scan, with or without contrast, should be made on a case-by-case basis, taking into account the individual patient's presentation, medical history, and risk factors, as emphasized in the 2021 ACR Appropriateness Criteria for syncope 1.

From the Research

CT Head for Syncope

• The decision to perform a CT head with or without contrast for syncope is based on various factors, including the patient's clinical presentation and medical history 3, 4.
• Studies have shown that the diagnostic yield of head CT scans in patients with syncope is relatively low, ranging from 1.1% to 3.8% 3.
• Noncontrast head CT is often used as the initial investigation in the emergency room for neurological symptoms, including syncope, and can help detect subtle vascular changes 5.
• The use of contrast in CT head scans for syncope is not explicitly stated in the provided studies, but it is generally used to help identify specific conditions such as tumors, infarcts, or hemorrhages 3, 5.
• Risk factors for serious intracranial conditions in patients with syncope, such as abnormal neurologic findings, age ≥ 65 years, trauma, warfarin use, and seizure/stroke history, may influence the decision to perform a CT head scan with or without contrast 3.

Diagnostic Yield and Risk Factors

• The diagnostic yield of head CT scans in patients with syncope is influenced by various factors, including the patient's age, medical history, and clinical presentation 3, 4.
• Studies have identified risk factors for serious intracranial conditions in patients with syncope, including abnormal neurologic findings, age ≥ 65 years, trauma, warfarin use, and seizure/stroke history 3.
• The quality of the studies referenced was strong, but more research is needed to develop a robust risk tool for identifying patients with syncope who would benefit from a CT head scan with or without contrast 3.

Clinical Assessment and Management

• The clinical assessment and management of syncope involve a structured approach, including a detailed medical history and physical examination 6, 7.
• The classification of syncope is based on the underlying pathophysiological mechanism causing the event, and includes cardiac, orthostatic, and reflex (neurally mediated) mechanisms 6.
• Patients with life-threatening causes of syncope should be managed urgently and appropriately, and may require further investigation, including CT head scans with or without contrast 6, 7.